Hi Alexsandr,

Well, the problem is more complex a bit. I see you configured OpenSIPs 
to add PATH header to REGISTER before sending it to FS. The address in 
PATH has UDP transport, so FS (if supports PATH) should send the calls 
back to OpenSIPS by using the address from PATH (with UDP). The contact 
in register has TLS transport (and you fwd it to FS as it is), but it 
should not be used directly by FS because of the presence and priority 
of PATH hdr.

So, my only explanation is that FS does not support / not configured to 
handle PATH, so that it uses the address from contact, which is TLS.

Regards,

Bogdan-Andrei Iancu
OpenSIPS Founder and Developer
http://www.opensips-solutions.com